Need a quick answer. TORQUING rear diff / bolt stretch/crak

Boiler · **Posted:** Sat Jul 25, 2009 9:25 pm

I'm heading out to change my rear diff fluid and put on my new cover. I've got brake cleaner to spray all over inside. Are these the proper steps:

1) Open and let it drain
2) Wipe out the bottom
3) Spray brake cleaner all over and kind of flood out the junk
4) Wipe it out
5) Clean off mating surface of old RTV
6) reassemble with my gasket.

QUESTION 1: After #4, do I need to wait a while to let the brake cleaner drip / evaporate? how long if so?

QUESTION 2: Finally, before I do anything I want to degrease the exterior. I had a leak and I want to clean it to make sure any new / continued leak is easily identifiable. Can I use something like simple green safely around seals and such? If not, is there a safe degreaser I can use and not worry about damaging anything?

JeepinJarhead03 · **Posted:** Sat Jul 25, 2009 10:04 pm

Q1:

Yeah, let the brake cleaner evap, it'll help keep cut down on grease and solvent drips across the mating surface

Prospect62 · **Posted:** Sat Jul 25, 2009 10:40 pm

I cleaned out a GM 10 bolt diff using Brake cleaner once...3 months and $1000 later I had a new rear end. I heard that brake cleaner ruins bearings/seals, etc.

My advice: NO brake cleaner, NO carb cleaner, NO gasoline, NO mineral spirits, NO paint thinner, NO laquer thinner... Just use kerosene or diesel. Neither of these will harm bearings or seals, and any minute traces of either will harmlessly dissolve in the gear oil.

I had a huge long thread on this on another forum from back when I was tearing apart my CJ. I'll be damned if I can find it now. The consensus was to not use brake cleaner in diffs.

tjkj2002 · **Posted:** Sat Jul 25, 2009 10:54 pm

Prospect62 wrote:

I cleaned out a GM 10 bolt diff using Brake cleaner once...3 months and $1000 later I had a new rear end. I heard that brake cleaner ruins bearings/seals, etc.

My advice: NO brake cleaner, NO carb cleaner, NO gasoline, NO mineral spirits, NO paint thinner, NO laquer thinner... Just use kerosene or diesel. Neither of these will harm bearings or seals, and any minute traces of either will harmlessly dissolve in the gear oil.

I had a huge long thread on this on another forum from back when I was tearing apart my CJ. I'll be damned if I can find it now. The consensus was to not use brake cleaner in diffs.

Brake cleaner is safe on the seals and the inside of your diff as long as it is allowed to evaporate or is cleaned up so as not to mix with the gear lube,that stuff was ment for cleaning drum brakes which have the axle seal right there also.Carb cleaner is pretty close to diesel and kerosene,and gas was used to clean bearing way before you where born and was used for decades to clean axle bearings and such.Mineral spirits,laquer thinner,and paint thinner is a no-no though.

KJ 119 · **Posted:** Sun Jul 26, 2009 8:42 am

If it is a beautiful day out and you have the time,here's a trick a hippie down the street taught me when I was changing my diff fluid.After draining diff,while cover is still off:

Put a jack on one side of axle and jack it up:Let that side drain for 45 min.
After 45 min put jack on other side of axle and let second side drain for an hour.

This will ensure that you have drained as much old fluid outta there as possible.

Put cover back on and filler up.

Boiler · **Posted:** Sun Jul 26, 2009 12:58 pm

Good idea. I was thinking I'd rotate my tires while letting things drain / dry anyway....so perfect

Boiler · **Posted:** Sun Jul 26, 2009 8:36 pm

Sigh...well the riddler cover came with grade 5 bolts (at least marked grade 5) and the lube locker gasket I bought said to torque all to 15 ft-lbs then do all again at 35 ft-lbs. Well, I just stretched the grade 5's til one cracked....I was able to get it out miraculously.

Should I get grade 8's, or turn down the torque? On one hand it may not get tight enough, on the other it might crack/strip something else...

JeepinJarhead03 · **Posted:** Sun Jul 26, 2009 9:18 pm

i used 8's torqued to 25 on my rockcrusher with a lubelocker and not a drip

it was probably just a cheep bad bolt

Boiler · **Posted:** Sun Jul 26, 2009 11:33 pm

well, apparently the stock and the replacements are 5's. I looked online and the recommended sae preload was 17 ft-lbs and they're asking for 35....

Tomorrow I'm going to find some # 8 bolts and put them to 25, which is the sae recommended torque for grade 8, 5/16-18 bolts.

I'll be wasting more time....writing an annoyed email....

JeepinJarhead03 · **Posted:** Sun Jul 26, 2009 11:45 pm

bolts that came with my RC were those allen head socketed type bolts which kinda ticked me off cause i didn't have a allen that would fit it at the time because it was before I lifted and the rearend was crammed up next to the gas tank :lol:

i'm very glad ya got the bolt extracted, i would def. write them an email and tell them they need to review that issue

tjkj2002 · **Posted:** Sun Jul 26, 2009 11:45 pm

Boiler wrote:

well, apparently the stock and the replacements are 5's. I looked online and the recommended sae preload was 17 ft-lbs and they're asking for 35....

Tomorrow I'm going to find some # 8 bolts and put them to 25, which is the sae recommended torque for grade 8, 5/16-18 bolts.

I'll be wasting more time....writing an annoyed email....

For what? For over torquing a bolt? That's why the cover came with a tube of RTV.

Boiler · **Posted:** Mon Jul 27, 2009 1:20 am

The email will be to lubelocker. Riddler provided grade 5 bolts, which match the factory 8.25 diff. Can't fault them in trying to save a few cents...

But LubeLocker is specifying what torque to tighten to, and its is too large for grade 5 bolts (standard on the given axle) and it is also considerably larger than the SAE recommendation for grade 8 preload torque. You'd think that they would not specify torque thats too high, unless they're going to supply bolts or at least recommend that they be changed to meet their spec.

Snapping a bolt in a diff can be a pretty big problem for the majorty of people out there. And a pita, not to mention a delay, for everyone else.

Boiler · **Posted:** Mon Jul 27, 2009 1:23 am

I was amazed that the bolt didn't break completely. I heard a little pop and stopped, and when I pulled it out the bolt was stretched, twisted, and had started to tear on BOTH sides, all in the same area...right where it would have been sticking out of the diff.

I showed it to Tony and his jaw just dropped. I was sure I was going to be hunting down an easy out but it came right out.

2-old · **Posted:** Mon Jul 27, 2009 3:24 pm

I tightened mine to 30 ft lbs. I think they me be original bolts, whatever they are.

Here is where I got my info'
http://www.jeepkj.com/forum/showthread.php?t=28670

Boiler · **Posted:** Mon Jul 27, 2009 3:33 pm

With the thicker cover the stock bolts were only going to give me about 3 threads engagement. Especially at 35 psi, I think I would be in danger of stripping out the diff or the bolts if I used those.

Today I got some grade 8 bolts, 1/4" longer than stock, and I plan on torquing to 25-30 and calling it a day.

Need a quick answer. TORQUING rear diff / bolt stretch/crak

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